For many years it has been shown that not all carbohydrate sources have the same effect on blood sugar levels (if consumed by itself). Thus, different foods with the same amount of carbohydrates can lead to a completely different increase in blood sugar levels. This differential effect is called “glycemic index” and divides the food regarding to their effect on blood sugar levels. Here, glucose serves as the reference value and is assumed to be 100. If one plots the course of the blood sugar levels in a diagram, then the GI defines the area under the curve of the blood sugar values. A GI of 50 means that the increase in blood sugar in this food is only half of the increase in glucose.
Foods that cause a rapid and / or high rise in blood sugar levels get a high GI. However, foods that only have a slight or slow effect on blood sugar levels have a low GI. The latter cause the blood sugar level to be elevated for a longer period of time, while it drops just as quickly in the case of fast-rising foods.
Incidentally, the same foods in different people may well lead to a different increase in blood sugar levels. The values given in the literature are therefore only an approximation, therefore there are also different tables for this. In addition, the information is only valid for the individual food and never for food combinations. The combination of white rice with turkey meat results in e.g. to a much slower rise in blood sugar than in white rice alone and thus has a lower GI. One should therefore never stubbornly regard tables on the GI as “bible”, but rather see it from a theoretical point of view.
Nevertheless, you should try to avoid strong blood sugar fluctuations, as a strong drop can lead to headache, weakness, dizziness, sweating, decreasing ability to concentrate, blurred vision and, above all, cravings. Low GI foods are always preferable to those with high GI.
|Fig.2 Foods and their glycemic index range|
|Foods that cause a fast and high blood sugar increase||White bread, honey, rice cakes, corn flakes, sweets, cola|
|Foods that cause an average increase in blood sugar||Potatoes, bananas, white sugar, fruit juices, chocolate, white rice, corn|
|Foods that cause a slow and flat rise in blood sugar||milk, yogurt, fruit, pasta, legumes, vegetables, nuts, oatmeal, ezekiel bread|
When looking at the GI table, a few things stand out, e.g. that “whole grain”-versions always have a lower GI than the regular products. As expected, junk food is at the top of the list.
By the way, spaghetti has a lower GI if it is not boiled soft, but is still “al dente”, which can be applied to all other types of pasta. Soft- and well-cooked pasta is digested faster and thus made faster available to the organism. That’s why pasta “al dente” can be preferred. By the way, the GI of pasta also varies due to their different thicknesses and lengths.